“K42R8”, a new forage oat variety showing extremely early heading and crown-rust resistance under late-summer sowing conditions

Oats (Avena sativa) are an important forage crop and are mainly sown in late summer in the Kyushu region of Japan, which means they are sown between late August and early September and harvested around December, ensuring forage production during the winter season. Oat varieties for late-summer sowing are required to have several adaptive traits, such as extremely early heading, crown-rust resistance, and lodging resistance, resulting in an expansion of the appropriate sowing period, producing stable foraging. A new variety for late-summer sowing, “K42R8”, was developed in the present study, which shows stable heading in December, even when sown in late September in the Kyushu region, and has enhanced crown-rust resistance. “K42R8” heads as early as one of the earliest oat varieties, “Kyushu 15”, in the appropriate sowing period and slightly later with late sowing. On the other hand, most plants of “K42R8” showed complete panicle emergence at harvest time with late sowing, as “Kyushu 15” does, and therefore it was felt that “K42R8” stably reached heading in winter even when cultivated by late sowing. Although the dry matter yield of “K42R8” in late sowing is 8% lower on a 2-location average over two years than that of “Kyushu 15”, it is considered that “K42R8” is enough to satisfy demands from forage producers because the yield of “K42R8” was equal to or greater than that of “West”, which is the most common variety in Japan. In addition, “K42R8” showed stable resistance to crown rust during late-summer-, fall-, and spring-sown cultivation in the field. It is expected that “K42R8” can be utilized in warm regions of Japan, from Kanto to southern Kyushu, contributing to stable forage production through risk reduction against bad weather and task distribution by expanding the appropriate sowing period. The present study also demonstrated that “K42R8” showed greater crown-rust resistance, and thus it is hoped that “K42R8” may become widespread as a novel crown-rust resistant variety in oat cultivation.